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' C. G. OLSON MACHINE FOR PRODUCING ABRASIVE HELICOIDS Filed Oct. 31 1921 3 Sheets-Sheet 1 July 15 ,1924. T

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macnmn FOR rnonucme an a Application filed October 31, 1921. Serial no. 511,795.

To all whom it may concern:

Be it known that I, CARL G. OLSON, a citizen. of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Machines for Producing Abrasive Helicoids, of which the following is a specification. My invention relates to machines for producing abrasive helicoids or grinding hobs. My machine operates upon the principle shown in my copending application for methodof producing abrasive elements, filed October 12, 1921, Serial No. 507,219; The objectof my present invention is to provide means 'for producing. such abrasive helicoids or grinding elements.

I accomplish this object by the mechanism illustrated in the accompanying drawings in which a Figure 1 is a front elevation partly in section of one form of machine embodying the invent-ion.

Figure 2 is a plan View of the right end :portion of Figure .1.

Figure 3 is an enlarged detail showing the cooperative relation of the scarifying or I dressing tool. with the work.

Figure 4 is a diagrammatic view illus trating the principle of operation of the scarifying tool.

Figure 5 is a plan View showing a modified form of machine embodying the invention. This second type is adapted for the production of abrasive helicoids whose general form is conical.

Figure 6 is a front elevation of the parts shown in Figure 5.

Figure 7 is a perspectivevicw of a multipointed scaritying or dressing tool, showing it-in'position on the work.

Figure 8 is a detail showing a modified form of mechanism in which diamond point instead of traveling-in a plane orbit, travels in an orbit a part or all of which is warped or at least does not lie in any.

mentioned applications; I have discovered that spur gears and similar articles may be' round by a method which is continuous in distinction to the indexing method heretofore in,.vogue. My continuous method employs an abrasive element, either cylindrical or conical in its general configuration, on which is formed a continuous abrasive thread or helicoid. This abrasive element operates somewhat after the manner of a hob, andthe gear to be ground (in fact, a complete stack of gears), may be completely ground as a result of a single setting of the machine. I have solved the problem of producing such abrasive elements by employing the. method described in the said method application and by constructing a machine forming the subject of the present application. One of the specific objects of my present invention may be thereforesaid to be the provision of a machine capable of operating upon the principle described in my said method application." According to' that method the abrasive helicoids are given their final form by a scarifying tool, such as a diamond point, rotating at high speed in a certain orbit. In some cases the orbit lies in a plane perpendicular to the axis of the work. In other cases it lies in a plane oblique to the axis of the work, and in still other cases it does not lie in any single plane.

The mechanism for taking care of these three situations will be described in the order mentioned.

Referring first to the type one, shown particularly in Figures 1, 2 and 3, the machine has a main frame 1 supporting three columns 2, 3, 4. The work 6 is rigidly fastened to'a' work arbor 8 which is 1ournaled in a sleeve 9 which slides longitudinally in the columns 2, 3, bi'it -is prevented from rotating by splines 10. It willbe understood that grinding elements have to be redressed more or less frequently in order to maintain their proper configuration, and thus accuratelyrgrind the gear wheel or other object upon which they are to work. When the abrasive element is to be used as .a grinder it will rotate at high speed. When it isto be dressed it willrotate at low speed. It is desirable to produce a machine capable of rotating the abrasive element at a high s eed for grinding purposes and at slow spec for dressing purposes. The present invention is not concerned with the highs eed rotation nor the use of the abrasive he icoid,'butrather with the producing -(dressin or scarifying) of the abrasive helicoidr eremorass is provided with a bearing 108 which is in the form of a clamp adapted to hold the housing 44 of the tool spindle 38. The spindle carries the scarifying tool 36, the parts being so arranged that the axis of the spindle is parallel to the axis of the work arbor. The spindle is rotated by a sheave 110 driven by a belt 111.

In operating this type of machine the I operator starts the belt 86,. which causes the 'work to rotate at slow speed without shifting axially. The rotation of the work arbor is transmitted to the lead screw 98 by the. worm and gear mechanism, with the result that the tool 'spindle travels obliquely at the same angle as the slope of the conical helicoid. The operator also starts the belt 111 which rotates the scarifying'or dressing tool at high speed, and this dresses the surface of the helicoid upon the same principle as before. scarfs are produced inthe helicoid, and as the work revolves and the tool travels the cutsor scarfs-will, in the aggregate, cover the entire surface to be dressed.

It may happen that abrasive helicoids are required in which a profile of the helicoid will show -a compound curve, as illustrated in Figure 8. In such case the scarify-ing tool cannot travel merely in a plane orbit, but must travel in an orbit part of which is warped or at least lies outside of the plane. Referring to this type of work the the rear end o'f'the housing, and has a nose 135 which engages a cam 136 formed at the rear end of said housing. The result is that as the spindle rotates it also shifts axially,

and by properly forming the cam any desired modification of the orbit of the grind-.

ing tool maybe produced. A coiled compression spring 140 surrounds the spindle between the forward end of the housing and the back of the tool 36 thus yieldingly keeping the collar at all times in contactwith the cam surface at the rear end ;of the housing.

, Fromthe foregoing it will be seen that my machine is capable of producmg a' series of arcuate cuts or scarfsin an, abrasive A multitude of'a-rcuate cuts or- A collar helicoid to dress the same or true it to its proper and desired form. In'order to accomplish this, it is not necessary that the tool rotate with any specific timed relation to the rotation of the work except that the speed of the tool must be great enough compared to the speed of the work to cause the arcuate scarfs in the aggregate to cover the entire he'licoidal surface-to be dressed. The machine goes further however, and causes this high speed tool, whose point is eccentric to its axis, to travel at a definite rate of speed in proportion to the helicoid. The drawings show that in practice the work may travel relatively to the tool or the tool may travel relatively to the work. The drawings also show that a single or a multiple scarifying tool may be employed and they also show that the axis of the tool may either be parallel to the axis of the workor oblique to it.

Having thus described my invention what I claim as new and desire to secure by Letters Patent, is

' 1. A machine for dressin preformed surfaces, having a pointed scarifying tool, means for causing it to revolve about an axis non-coincident with the point of the tool, and a rotatable work holder having an axis non-coincident with the axis of rotation of the scarifying tool, the plane defined by the point of the tool beingapproximately at right angles to the axis of the work and the point of the tool traveling in an orbit only a part of'which lies in the surfaceAto be produced,and the scarfs in the aggregate enveloping the surface to be produced.

2. A machine for producing abrasive helicoids, having a scarifying tool, means for causing it to rotate about an axis distant from the point of the tool, means for causing successive portions of the helicoid to pass in contact with said tool for a limited arc of its orbit, and means for causing relative travel of the tool and work in comformity with the lead of the helicoid.

3. A machine for producing abrasive elements, having a pointed dressing tool, means for causing it to travel at high speed 1n a definite orbit, and means for rotating the' 4. A machine for producing abrasive helicoids, having a pointed dress n tool,'means for causing it to travelat hig speed in a definite orbit, means for rotating the work Hit work at slow speed to bring successive porat .slow speed to bring successive portions of it into contact with said toolfor a limited arc of the orbit thereof, and meansfor sitween the tool and the work in conformity with the lead of the helicoid.

5. A machine for dressing 3. warped surface in the form of an oblique helicoid having a cylindrical envelope (as shown in Figures 1 to 4) said machine having means for rotating the helicoid, a spindle, a scarifying tool supported by said spindle at a distance from theaxis thereof, and means for supporting the spindle in such position that an arc of the orbit of the tool will intersect the envelope of the helicoid, the supporting means holding the spindle at. an oblique angle to the axis of the work such that the intersecting arc of the orbit will lie substantially in the Warped surface, throughout the major portion of the intersected arc of the envelope.

6. A,machine for dressing a warped surface in the form of an oblique helicoid having a cylindrical helicoid, said machine having means for rotating the helicoid, a spindle, a scarifying tool supported by the spindle at a distance from the axis thereof, means for supporting the spindle in such position that an arc of the orbit of the tool will intersect the envelope-of the helicoid,- the supporting means holding the spindle at an oblique angle to the axis of the work such that the intersecting arc of theorbit will lie substantially in the warped surface throughout the major portion of the intersected arc .of the envelope, means for causing relative travel of the tool and the work in conformity with the lead of the helicoid thereof.

7. A. machine for dressing abrasive helicoids having a pointed'tool, means for causing it to rotate about an axis distant from the point of the tool, means for rotating the work to cause successive portions of the helicoid to pass in contact with the tool for a limited arc of the orbit thereof, means for causing relative travel of the tool and work' in conformity with the lead of the helicoid, and means for simultaneously varying the distance between the axis of the tool and the axis of the work.

8. A machine for. dressing preformed surfaces formed on bodies whose cross sections are circular when taken at or nearly at right angles to the axis of the work, said machine having a plurality of pointed scarifying tools, a rotatable tool holder whereon said tools are arranged withtheir points lying substantially in a circle at right angles to and coaxial with the axis of revolution of the holder, and a rotatable work holder having'anaxis lying in the same plane as the axis of-the tool holder and roughly par-- allel with it, and in such position that the circle defined by the points of the tool will intersect the circle of cross section of the work taken at the point of contact of the tool with the work.

1 In witness whereof, I have hereunto subscribedmy name.

' CARL G. OLSON. 

